Diurnal variation in the P300 component of human cognitive event-related potential

Diurnal variation in the P300 component of the human cognitive event-related potential (ERP) was examined. The P300 component is considered to be a measure of neuroelectric activity related to cognitive functions such as attention allocation and information processing. Nine diurnally active healthy male subjects whose sleep-wake rhythms were synchronized prior to the experiment were studied. The P300 components oral temperature, heart rate, left- and right-hand grip strength, reaction time, subjectively rated sleepiness, attention level, and fatigue were measured at 08:00, 11:00, 14:00, 17:00, and 20:00. Significant diurnal variations in P300 latency, P300 amplitude, oral temperature, heart rate, left- and right-hand grip strength, subjectively rated sleepiness, and attention level were observed. The P300 latency at 08:00 was significantly longer than at 11:00, 17:00, and 20:00, while the P300 amplitude at 08:00 was significantly greater than at 17:00 and 20:00. The P300 latency was correlated positively with subjectively rated sleepiness and negatively correlated with subjectively rated attention level. These results suggest the existence of diurnal variation in human cognitive functions.     

Spatial gradient of P300 area of the brain visual evoked potential in the brain-computer interface paradigm

In 12 adult healthy subjects we studied Brain-Computer-Interface recognition of different intended letters by the square of P300 wave in the averaged VEP. Horizontal and vertical spatial gradient of this square was studied as well as tuning acuteness of visual attention to a significant letter. High acuteness of this tuning was found (width of the tuning curve at its half height was equal to 1.6 grad) independent of the letter position on the letter matrix. Horizontal and vertical gradient of P300 were found to be very similar, but in the half of cases the first one revealed some kind of the "lateral inhibition": decrease of P300 square for the columns neighboring to the meaningful one. Tuning acuteness was found to be reliable and directly interrelated with P300 square. The data are discussed in relation to selectivity of the local visual attention.     

Amplitude-time parameters of long-latency components (N1, N2 and P300) of acoustic evoked potential of healthy examinees of young and mature age

The aim of study was to track a cumulative changes of amplitude-time parametres of components N1, N2 and P300 of acoustic evoked potential in experimental situations different in complexity (at the account and listening of sounds) and to compare the received distinctions at examinees of young and mature age. ERP were recorded at 12 healthy subjects from 18 to 22 ages and 12 subjects from 32 to 59 ages. The two-stimuli oddball paradigm was used. It is revealed that components N1, N2 and P300 recorded in the situation of the listenings of sounds without any preliminary instruction do not differ at persons of young and mature age. At examinees of younger age the biger amplitude of component N1 is noted at the account of sounds in comparison with listening whereas the latency of the one do not change depending on complexity of the task. It is shown that component N2 has stability of latency in relation to age and an experimental situation. The amplitude of component N2 is above at the account of sounds in both age groups. The amplitude-time parametres of component P300 do not differ at examinees of different age in a problem of listening of sounds. The revealed features of components N1, N2 and P300 at examinees of young and mature age in experimental situations different in complexity, allow to assume that with the years at the person adaptive mechanisms which allow carrying out successfully of the task.     

P300 component changes of the auditory event-related potential in the patients with typical and atypical panic attacks

84 patients with panic disorders and 36 healthy control subjects with use of clinico-neurologic technique, psychometric, neuropsychological and the neurophysiological method of auditory event-related potentials P300 were examined. Patients with panic disorders were characterized by the raised level of anxiety, depression and cognitive function disturbances in the form of decrease of short-term memory and attention insufficiency in comparison with the healthy control subjects. Patients with atypical panic disorders differed from the patients with typical panic disorders by lower level of anxiety, a greater degree of depression and more expressed cognitive function disturbances. In comparison with the healthy control subjects with atypical panic disorders the decrease of P300 peak amplitude was observed, with typical--its augmentation. It is supposed, that P300 peak change is bound to dysfunction of temporal-limbic-reticular brain structures.     

Study of the letter and word recognition by the brain-computer-interface with P300 wave of human visual evoked potential

In four adult healthy subjects in 18 experiments, we studied Brain-Computer-Interface recognition of different intended words by P300 wave in the VEP. The set of optimal characteristics of visual stimulation which rise reliability of recognition up to 100 %, as well as effective registration locus (Pz) were determined. It was found that the best processing criteria for letter recognition were: P300 square and superposition of all three criteria (P300 amplitude, square and covariation coefficient).     

Specific changes in auditory cognitive evoked potentials in those who participated in the liquidation of the Chernobyl accident: II. Analysis of the late P300 component

An integrated neuropsychological study and recording of auditory cognitive evoked potentials (EPs) using the three-stimulus oddball paradigm was performed in groups of ten subjects who participated in the liquidation of the consequences of the Chernobyl accident aged 50.5 ± 4.0 years and ten healthy subjects aged 47.0 ± 6.0 years. The neuropsychological study showed impairment of higher mental functions, including aspontaneity, fatigability, a decrease in the auditory-verbal and visual memories, and higher motor function deficiency, in cleanup workers (usually referred to as liquidators). Analysis of the amplitude and time characteristics of the P300 component of the auditory cognitive EP showed a decrease in the amplitude of this component in all cortical areas of liquidators in both experimental situations and for all stimuli compared to healthy subjects of the same age. Analysis of the latent period (LP) of P300 in liquidators showed the most distinct increase in the situation of passive audition for all types of stimuli. Analysis of the patterns of reactive rearrangements in different experimental situations showed that the P300 LPs of healthy subjects were similar for all types of stimuli during passive audition and were higher for the significant stimulus in the situation of counting. Liquidators were characterized by an type of response, with the LPs of responses to most stimuli increased in both experimental situations. Analysis of regional changes in the P300 LP showed that the differences in the P300 LP between the groups were the largest in the frontal areas of the left hemisphere. In addition, liquidators exhibited “uneconomical, excessive” responses as compared to normal responses, which suggests a decrease in the attention and memory capacities and could contribute to the impairment of higher mental functions. The changes in the amplitude and time characteristics of the P300 component of auditory EPs suggest deceleration of perception, processing, and analysis of information combined with weakened inhibition. The changes found in liquidators are similar to those observed in elderly people, which supports the hypotheses on accelerated brain aging and on pathological aging caused by low-dose irradiation.     

Gender differences in medium-latency acoustic evoked potentials

Medium-latency acoustic (auditory) evoked potentials (MLAEPs) were recorded in 30 men and 30 women. The MLAEPs recorded in the left and right mastoid derivations were found to be asymmetrical, the lateral differences depending on the sex: binaural stimulation and stimulation of the right ear yielded a higher total amplitude of the set of medium-latency components in the right derivation in men and in the left derivation in women. If the left ear was stimulated, there were no sex-related differences in MLAEP asymmetry. The data are discussed in terms of gender differences with respect to functional specialization of the cerebral hemispheres.     

噪声暴露对大鼠事件相关电位P300的影响及其海马水平的机制

目的：研究噪声暴露对大鼠事件相关电位（ERP）的影响及海马水平的机制。方法：雄性SD大鼠,随机均分为正常对照组（C组）、噪声暴露组（N组）。暴露条件：105dB白噪声2．5h／d×20d。观察试验过程中第0、7、14和20d ERP各波的峰潜伏期以及峰峰幅度值,并检测海马神经元尼氏体、NMDAR2B及胞内钙浓度的变化。结果：在实验第14d、第20d,噪声暴露组动物ERP P3a、P3和P3b的峰潜伏期显著增长,而且在噪声暴露20d后,大鼠海马齿状回以及CA1区尼氏体显著减少（P〈0．01）,齿状回、CA1及CA3区NMDAB2B的免疫反应强度显著降低（P〈0．01）,神经元胞内钙浓度显著升高（P〈0．01）。结论：噪声暴露可致事件相关电位的改变,这可能与其海马神经元尼氏体、NMDAR2B以及胞内钙的变化有关。     

Effect of seduksen (diazepam) on cortical P300 potentials evoked by neutral and emotional words

The influence of seduxen (diazepam) on cortical potentials P300 evoked by neutral and emotional words was studied in adult subjects having life conflicts. The therapeutic dose of seduxen (10 mg) had no significant effect on the amplitude of the late positive cortical response P300 to neutral words. Seduxen depresses the emotional activation of the cerebral cortex; that is manifested in selective elimination of those changes in latency and amplitude of P300 wave which are observed in response to emotionally significant words. Under the action of seduxen, the interhemispheric difference in the latency of cortical response disappears due to latency increase in the right hemisphere.     

Concentration effects of green odor on event-related potential (P300) and pleasantness

The effects of eight compounds, constituting the so-called "natural green odor", including leaf alcohol, on the event-related potential (P300) were investigated. In experiments with a series of single compounds, each of these eight compounds could be characterized by an overall change consisting predominantly of an increase, a decrease or no change in the amplitude of P300, whereas in experiments with a series of two-component mixtures, noticeable synergism could not be demonstrated, contrary to our expectation. Experiments with leaf alcohol (3Z-hexenol) performed at two concentrations showed a significantly different degree of pleasantness and an increase or decrease in the amplitude of P300 depending on their concentration, suggesting that concentration is important in odorant-presentation studies.     

Auditory evoked potential audiometry in fish

A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. First, our review compares AEP hearing thresholds to behaviorally gained thresholds. Second, baseline hearing abilities are described and compared in 111 fish species out of 51 families. Following this, studies investigating the functional significance of various accessory hearing structures (Weberian ossicles, swim bladder, otic bladders) by eliminating these morphological structures in various ways are dealt with. Furthermore, studies on the ontogenetic development of hearing are summarized. The AEP-technique was frequently used to study the effects of high sound/noise levels on hearing in particular by measuring the temporary threshold shifts after exposure to various noise types (white noise, pure tones and anthropogenic noises). In addition, the hearing thresholds were determined in the presence of noise (white, ambient, ship noise) in several studies, a phenomenon termed masking. Various ecological (e.g., temperature, cave dwelling), genetic (e.g., albinism), methodical (e.g., ototoxic drugs, threshold criteria, speaker choice) and behavioral (e.g., dominance, reproductive status) factors potentially influencing hearing were investigated. Finally, the technique was successfully utilized to study acoustic communication by comparing hearing curves with sound spectra either under quiet conditions or in the presence of noise, by analyzing the temporal resolution ability of the auditory system and the detection of temporal, spectral and amplitude characteristics of conspecific vocalizations.     

Visual evoked potential in guinea pigs

The present study was designed to establish visual evoked potential (VEP) as one of clinical tests for veterinary medicine. Experiments were carried out on eight adult male guinea pigs weighed 350 to 750 g. We investigated influences of click sound, luminous intensity and habituation on VEP patterns. The VEP of the guinea pig was composed of primary (P 10, N 20, P 30, N 40) and secondary (P 55, N 75, P 100, N 140) components, followed by a rhythmic after-discharge. Click sound with flash produced some unclear peaks in VEP, while click sound without flash elicited clear six peaks. These different components of the response to stimulation suggested that the acoustically evoked potential induced some peaks in VEP. With the intensity used in the present study, changes in luminous intensity resulted in unrecognizable difference among the VEPs. Early components of VEP were not clearly influenced by the habituation to stimulation. As the stimulation was repeated, rhythmic after-discharge seemed to be suppressed in the half of experiments.     

Early positive component of the tectal evoked potential ofSqualus acanthias during electrical stimulation of the optical nerve

The evoked potential of the tectum opticum during electrical stimulation of the optic nerve was studied in acute experiments on the dogfishSqualus acanthias L. The negative phase of the "classical" negative-positive evoked potential of the contralateral hemisphere of the tectum opticum was shown to be a complex potential, including an early positive component. A similar potential also was recorded from the ipsilateral hemisphere. Enhancement of this positive potential on insertion of the recording electrode deep into the brain, its resistance to functional block on application of potassium chloride to the brain surface, and recording a similar potential from the surface of the floor of the third ventricle after extirpation of the tectum opticum are evidence of the nontectal location of the source of this evoked potential component. On the basis of existence of a focus of maximal activity in the rostral zones of the brain beneath the tectum opticum, and disappearance of the early positive component during functional block and extirpation of this brain region, it is concluded that a leading role in the generation of this component is played by thalamic nuclei.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 16, No. 1, pp. 61–67, January–February, 1984.     

Time-frequency component analysis of somatosensory evoked potentials in rats

Background  

Somatosensory evoked potential (SEP) signal usually contains a set of detailed temporal components measured and identified in a time domain, giving meaningful information on physiological mechanisms of the nervous system. The purpose of this study is to measure and identify detailed time-frequency components in normal SEP using time-frequency analysis (TFA) methods and to obtain their distribution pattern in the time-frequency domain.     

Sustained potential shifts,alterations in acoustic evoked potential amplitude and bradycardiac responses to the onset of illumination in the goldfish (Carassius auratus)

Sustained potential shift's (SPSs) and changes in acoustic evoked potential (AEP) amplitudes were recorded from medullary and mid-brain regions in restrained goldfish (Carassius auratus) in response to the onset of illumination against a sensory background restricted to repetitive (1/s) acoustic stimulation. At the tectal surface, a long duration negative SPS, significant 5–10 s after the onset of illumination, was recorded with a maximum negativity of ca. 145 V. Changes in acoustic responsiveness were also most apparent in the mid-brain where attenuations in AEP amplitude of ca. 15% were recorded.In general, AEPs exhibited attenuated amplitudes in response to the onset of illumination, perhaps reflecting attentional rather than arousal processes, arousal generally being associated with heightened sensory responsiveness. Changes in the amplitude of the medullary AEPs were directly related to the magnitude of bradycardiac responses such that lesser attenuations of the medullary AEP were associated with greater magnitude bradycardiac responses, suggesting a possible interaction of attentional and arousal processes.In response to repeated onset of illumination, SPSs tended towards increasing positivity (increasing in positivity at the medullary surface; decreasing in negativity at the tectal surface). The attenuation of AEPs recorded from the medulla and mid-brain habituated in response to stimulus repetition.Changes in amplitude of AEPs (AEP) recorded from the telencephalon and the torus semicircularis region of the mid-brain were correlated with locally recorded SPSs. At the telencephalon, this correlation was inverse; enhanced AEP amplitudes being associated with SPS negativity, attenuated AEP amplitudes with SPS positivity. In the torus semicircularis, experiential changes in SPS and AEP were directly correlated. As the SPS is considered to reflect glial redistribution of [K⁺]_e (Roitbak 1983), glia may contribute to changes in measures of sensory responsivity, such as the AEP, during changes in behavioural state.Abbreviations AEP Acoustic Evoked Potential - AEP Event-related change in amplitude of AEP following onset of illumination - SPS Sustained Potential Shift - [K⁺]_e Extracellular concentration of K⁺